[Analysis API FIR] support generated temp properties

KTIJ-23492 (array index expression), KTIJ-23138 (inc/dec desugaring)

analysis/low-level-api-fir/testdata/getOrBuildFir/expressions/arrayIndexExpressionWithInc.kt

@@ -0,0 +1,6 @@
+// WITH_STDLIB
+fun main(args: Array<String>) {
+    val a = ArrayList<String>()
+    a.add("")
+    a[<expr>0</expr>]++
+}

analysis/low-level-api-fir/testdata/getOrBuildFir/expressions/arrayIndexExpressionWithInc.txt

@@ -0,0 +1,6 @@
+KT element: KtConstantExpression
+FIR element: FirConstExpressionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+Int(0)

analysis/low-level-api-fir/testdata/getOrBuildFir/expressions/incExpression.kt

@@ -0,0 +1,4 @@
+fun main(args: Array<String>) {
+    var nextUnnamedLibraryIndex = 1
+    val originalName = "${<expr>nextUnnamedLibraryIndex++</expr>}"
+}

analysis/low-level-api-fir/testdata/getOrBuildFir/expressions/incExpression.txt

@@ -0,0 +1,6 @@
+KT element: KtPostfixExpression
+FIR element: FirVariableAssignmentImpl
+FIR source kind: DesugaredIncrementOrDecrement
+
+FIR element rendered:
+R|<local>/nextUnnamedLibraryIndex| = R|<local>/<unary>|.R|kotlin/Int.inc|()